html {
  box-sizing: border-box;
}
* {
  margin: 0;
  padding: 0;
  box-sizing: inherit;
  &:before,
  &:after {
    box-sizing: inherit;
  }
}
body {
  width: 100%;
  height: 100vh;
  background-color: #fff;
  font-family: sans-serif;
  position: relative;
}

.ball {
  position: absolute;
  top: 0;
  left: 0;
  width: 100px;
  height: 100px;
  background: red;
  border-radius: 50%;
  margin-top: -50px;
  margin-left: -50px;
}

.pointer {
  position: absolute;
  width: 30px;
  height: 30px;
  border: 2px solid #0003;
  border-radius: 50%;
  transform: translate(-50%, -50%);
  animation: sink 1s steps(1) forwards;
}
@keyframes sink {
  0%,
  100% {
    opacity: 1;
  }
  50% {
    opacity: 0;
  }
}
